feat: 优化 Solution ID 命名机制并添加 GitHub 链接显示

- Solution ID 改用 4 位随机 uid (如 SOL-GH-123-a7x9) 避免多次规划时覆盖
- issue 卡片添加 GitHub 链接图标，支持点击跳转到对应 issue

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ccw/src/templates/dashboard-js/views/issue-manager.js

@@ -338,6 +338,14 @@ function renderIssueCard(issue) {
             ${t('issues.boundSolution') || 'Bound'}
           </span>
         ` : ''}
+        ${issue.github_url ? `
+          <a href="${issue.github_url}" target="_blank" rel="noopener noreferrer"
+             class="flex items-center gap-1 text-muted-foreground hover:text-foreground transition-colors"
+             onclick="event.stopPropagation()" title="View on GitHub">
+            <i data-lucide="github" class="w-3.5 h-3.5"></i>
+            ${issue.github_number ? `#${issue.github_number}` : 'GitHub'}
+          </a>
+        ` : ''}
       </div>
     </div>
   `;